Batteries

The batteries powering the electric Audi are Chinese Aviation Lithium Battery (CALB) cells with a LiFePO4 chemistry. The total pack is comprised of 34, 130AH cells for a nominal pack voltage of 112v, maximum power output of 72.8kW, and a maximum energy capacity of 14.5kWh. The charger is an Elcon PFC 1.5kW charger programmed for “33 cells” in order to undercharge the pack slightly and extend its life.

 264662_10150713682310176_4826254_nThe batteries were purchased from calibpower.com, but their website seems to have gone down. It was a simple ordering process, and I could pay via Paypal. About a week later, the batteries were shipped to me in 2 crates via UPS freight.

285410_10150732512340176_5099426_nHere batteries are test fitted onto a rack. The rack currently bolts down to the bumper mounts and cargo anchors with 4 M12 bolts. The battery racks are bring redesigned to be more enclosed and secured to the chassis.

IMG00287-20110822-1400All 34 batteries are in the trunk. Another reason for a redesign of the battery racks is the amount of usable space in the trunk and the limited distance between the edges of the trunk and the battery terminals. The redesigned battery rack will move the batteries forward slightly and allow for some usable trunk space.

As always, with great power comes great responsibility, in the form of using properly rated and sized fuses. Low voltage, high current fuses intended for forklifts and car audio are not suitable for high voltage traction battery packs. I’m using a Bussmann 500a 150v DC fuse found here.

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I’ve seen many conversions on evalbum with questionable circuit protection, using AC circuit breakers, 12v fuses, ANL forklift fuses, etc. Fusing shouldn’t be skimped, you should be able to depend on a fuse preventing an electrical fire or melting your car down.

In the event of an emergency, there is a Tyco kilovac EV200 contactor in the trunk with the batteries. Tyco kilovacs can be found between $30 and $60 either used or as surplus on Ebay, for their current handling capabilities, small packaging, and hermetically sealed contacts. The contactor itself is connected to an emergency stop switch which took place of the front cigarette lighter to isolate all high voltage to the trunk.

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In order to get power from the trunk to the engine bay, 1/0 gauge welding cable runs inside orange flexible electrical conduit where the exhaust system used to be.IMG00305-20110828-1436

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